1. Technical Field
The present invention relates to a transmission screen preferably employed in a rear projection display or the like provided with a CRT, a liquid crystal light bulb or a DLP as a light source. More particularly, the present invention relates to a transmission screen capable of preventing the reduction of contrast by external light.
2. Background Art
Studies have been made to suppress the reduction of contrast in images displayed on a rear projection television (hereinafter, abbreviated to “PTV”). Unnecessary stray light produced by reflecting image light emitted by a projection light source by lens elements included in the transmission screen and emitted toward the viewer and external light emitted by lighting fixtures, fallen on the transmission screen and reflected toward the viewer are representative factors of the reduction of contrast in images displayed by the PTV.
The former factor can be eliminated to suppress the reduction of contrast in images by a method disclosed in, for example, Patent document 1 that places a light-absorbing member or a light scattering member on the plane surface of a Fresnel lens sheet included in the transmission screen to absorb or scatter unnecessary light. Another method of eliminating the former factor to suppress the reduction of contrast in images disclosed in, for example, Patent document 2 forms a light-absorbing part in or disperses a light-absorbing material in a Fresnel lens sheet included in the transmission screen to absorb unnecessary light by the light-absorbing part or the light-absorbing material.
The latter factor can be eliminated to suppress the reduction of contrast in images by incorporating a Fresnel lens sheet provided with an antireflection coating into a transmission screen to suppress the reflection of external light or by incorporating a Fresnel lens sheet containing a light-absorbing material into a transmission screen to suppress the reflection of external light.
Patent document 1: JP 4-163539 A (FIG. 1)
Patent Document 2: JP 6-148407 (FIGS. 2 and 4)